JP4091083B2 - Tire internal failure detection device and tire internal failure detection method - Google Patents

Description

  The present invention relates to a tire internal failure detection device and a tire internal failure detection method capable of detecting an internal failure occurring inside the tire in a state in which a vehicle including wheels equipped with tires is running. About.

  If a failure such as separation occurs inside the tire for some reason while the vehicle is running, if the vehicle continues to run with the failure occurring, for example, the tire may suddenly burst and become unable to run As a result, there is also a risk of causing a traffic accident. If a failure such as a rubber-belt that constitutes the tire or damage (separation) that separates the rubber from the rubber occurs inside the tire, such a failure is detected immediately and a warning is given to the passengers. This is very important for safety. For this reason, pre-shipment inspection using, for example, an X-ray non-destructive testing machine is performed on product tires. At the time of manufacturing the tire, for example, in the molding / vulcanization process, when there is an internal failure due to foreign matter mixed into the tire raw material, the internal failure can be found by this pre-shipment inspection. In the case of low durability products due to tire structure, rubber physical properties, etc., as a product test, the durability is evaluated by the indoor drum durability test that is usually performed, and the tires that are actually mounted on the vehicle in the market are evaluated. A durability index is obtained.

  However, for example, in the pre-shipment inspection using an X-ray non-destructive testing machine, it is possible to detect the complete separation inside the tire, but it is possible to detect the separation that occurs and develops due to the load during driving ( Cannot be predicted). Moreover, even if the durability index can be obtained by the indoor drum durability test, in such a durability test, the load state (on the product tire that is actually used while being mounted on the vehicle) ( Only a small part of the load state (loading capacity, air pressure, road temperature, running pattern, etc.) can be reproduced. That is, in the endurance test, the load state of each product tire that is actually used in a state where it is mounted on the vehicle cannot be reproduced individually. By using only the durability index obtained in the durability test conducted under such a limited condition, it is possible to separate each of the product tires that are actually used in the vehicle. It is not possible to determine whether or not an internal failure has occurred. For this reason, with respect to product tires that are conventionally used in a state where they are actually mounted on a vehicle, an apparatus capable of quickly detecting an internal failure such as a separation that occurs while the vehicle is running, and A method was desired.

Conventional means for detecting a failure that has occurred in a tire mounted on a vehicle include, for example, Patent Documents 1 and 2 below. The following Patent Document 1 is configured to measure changes in the vibration and sound of a tire mounted on a running vehicle, analyze the frequency of these measurement results, and determine the tire state using the result of the frequency analysis. Thus, a tire abnormality detection system that can accurately notify the driver of tire abnormality is disclosed. In Patent Document 2 below, when the tire air pressure and the tire internal temperature are detected, the air pressure is lower than a preset value, and the tire internal temperature is higher than a preset temperature. There is provided a tire monitoring system that can accurately detect a tire puncture and an abnormal state that may cause a tire puncture by determining that the tire is abnormal.
JP 2003-80912 A JP 2003-72330 A

  In the tire abnormality detection system described in Patent Document 1, tire abnormality is detected based on measured changes in tire vibration and sound. However, in an actual vehicle, the state of tire vibration and sound varies depending on changes in various factors, such as the road surface on which the vehicle actually travels and the driving conditions (speed and load) of the vehicle. Change. The change in the state of vibration or sound contains a lot of components corresponding to such changes in the road surface state and the running condition of the vehicle, that is, noise components. In the tire abnormality detection system described in Patent Document 1, the abnormality of the tire cannot be detected with sufficient accuracy due to the influence of such a noise component. Moreover, in the tire monitoring system described in Patent Document 2, a failure in the tire is detected based on the tire air pressure and the tire internal temperature. However, it has been confirmed by the inventor of the present application that no significant change appears in the tire air pressure and the tire internal temperature when a failure such as separation occurs in the tire. Specifically, a vehicle equipped with a tire with no internal failure was allowed to travel continuously for 1 hour, and the tire temperature and the tire internal pressure before and after traveling were detected. Then, the same tire with the same separation (same size and air pressure) is mounted on the same vehicle, and the vehicle is continuously run for 1 hour, and the tire temperature and the tire internal pressure before and after running are respectively set. Detected. As a result, regardless of whether or not an internal failure (separation) has occurred inside the tire, no change in tire internal pressure was observed before and after continuous running for 1 hour, and there was a significant difference in temperature change. There wasn't. In the tire monitoring system described in Patent Document 2, a failure such as a separation occurring inside the tire cannot be detected with sufficient accuracy.

  Therefore, in order to solve the above-mentioned problems, the present invention detects an internal failure occurring inside the tire with high accuracy in a state where a vehicle including wheels equipped with tires is running. An object of the present invention is to provide a tire internal failure detection method and a tire internal failure detection device.

  In order to solve the above-mentioned problems, the present invention is an apparatus for detecting an internal failure occurring inside the tire in a state where the vehicle is traveling, in a vehicle including wheels equipped with tires. Tire information acquisition means for acquiring tire information related to the rolling tire, and deformation amount derivation means for deriving a deformation amount of a ground contact portion of the tire while the vehicle is traveling based on the tire information. The evaluation value calculating means for calculating an evaluation value for determining whether or not the internal failure has occurred is compared with the calculated evaluation value and a predetermined reference value based on the derived deformation amount And determining means for determining whether or not an internal failure has occurred inside the tire. A tire internal failure detection device is provided.

  In the present invention, the tire information acquisition means acquires, as the tire information, time-series acceleration data of a predetermined portion of the tire that is generated when the rolling tire receives an external force from the road surface. Preferably, the deformation amount deriving unit obtains the deformation amount of the ground contact portion of the tire using the time-series acceleration data of the tire acquired by the tire information acquisition unit.

  Further, the deformation amount deriving means extracts time-series acceleration data based on tire deformation from the time-series acceleration data, and performs second floor time with respect to the time-series acceleration data based on the tire deformation. It is preferable to calculate the amount of deformation of the tire by performing integration to obtain displacement data.

  The deformation amount deriving means obtains at least two deformation amounts in the tire in the circumferential direction and the tire width direction deformation amount in the tire contact portion, and the evaluation value calculating means includes: Preferably, the evaluation value is calculated based on a deformation amount in two directions of the circumferential deformation amount in the tire contact portion and the width deformation amount in the tire contact portion.

Further, when the maximum value of the circumferential deformation amount at the ground contact portion of the tire is X _max and the maximum value of the width direction deformation amount is Y _max , the evaluation value is X _max / Y _max or Y _max / It may be a value expressed using any one of _Xmax .

The evaluation value is preferably a value represented by using either tan ⁻¹ (X _max / Y _max ) or tan ⁻¹ (Y _max / X _max ).

Further, when the maximum value of the circumferential deformation amount at the ground contact portion of the tire is X _max and the maximum value of the width direction deformation amount is Y _max , the evaluation value may be X _max × Y _max. Good.

  Further, the deformation amount deriving step obtains a circumferential deformation amount of the tire in a ground contact portion of the tire, and the evaluation value calculating step calculates the evaluation value based on a maximum value of the circumferential deformation amount. Is preferred.

  Further, the deformation amount deriving step obtains a tire width direction deformation amount at a contact portion of the tire, and the evaluation value calculating step calculates the evaluation value based on a maximum value of the width direction deformation amount. Is preferred.

  The present invention is also a method for detecting an internal failure occurring inside the tire in a vehicle including a wheel fitted with a tire in a state where the vehicle is running, the rolling A tire information obtaining step for obtaining tire information relating to a tire; a deformation amount deriving step for deriving a deformation amount of a ground contact portion of the tire while the vehicle is running based on the tire information; and the derived deformation An evaluation value calculating step for calculating an evaluation value for determining whether or not the internal failure has occurred based on the amount, and comparing the calculated evaluation value with a predetermined reference value, And a determination step of determining whether or not an internal failure has occurred inside. A tire internal failure detection method is also provided.

  According to the tire internal failure detection method and the tire internal failure detection device of the present invention, in a vehicle including a wheel on which a tire is mounted, an internal failure occurring inside the tire in a state where the vehicle is running, It can be detected with high accuracy.

  Hereinafter, a tire internal failure detection apparatus and a tire internal failure detection method of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  FIG. 1 is a schematic configuration diagram illustrating a tire internal failure detection device 10 (device 10), which is an example of a tire internal failure detection device according to the present invention. The device 10 is provided in a vehicle 12 provided with four wheels 14a to 14d. These four wheels 14a to 14d are wheels formed by mounting the same type of tires (tires having the same tire size, tire rim width, belt structure, tire filling air pressure, etc.) 15a to 15d, respectively. is there. The apparatus 10 includes sensor units 16a to 16d, a data processing unit 20, and a display 34. The sensor units 16a to 16d are respectively provided on the four wheels 14a to 14d. When the vehicle 12 travels on the road surface, the tire 15 of each wheel is generated by receiving an external force from the road surface. The acceleration information of a predetermined part is acquired and transmitted by a wireless signal.

  The data processing unit 20 receives the radio signals transmitted from the sensor units 16a to 16d, respectively. Then, deformation acceleration information in the tire radial direction of each tire, deformation acceleration information in the tire circumferential direction of each tire, and deformation acceleration information in the tire width direction of each tire are extracted from the received radio signal. Then, from the extracted deformation acceleration information in the tire radial direction, the contact timing of a predetermined portion of the tire 15 (the acceleration sensor 2 fixed to the inner peripheral surface of the tire cavity region arrives at the center position of the tire contact surface (closest). ) Timing) is obtained, and using this contact timing, the deformation amount in the tire circumferential direction of the contact portion of each tire is derived from the extracted deformation acceleration information in the tire circumferential direction, and the extracted deformation acceleration information in the tire width direction is extracted. Thus, the deformation amount in the tire width direction of the ground contact portion of each tire is derived. Then, the data processing unit 20 determines whether or not an internal failure has occurred in each tire based on the deformation amount in the tire circumferential direction of the ground contact portion of each tire and the deformation amount in the tire width direction of the ground contact portion of each tire. An evaluation value is calculated. Then, the data processing unit 20 compares the calculated evaluation value with a predetermined reference value to determine whether or not an internal failure has occurred in the tire. In this embodiment, as will be described later, deformation acceleration information in the tire radial direction is used in order to accurately derive the contact timing of a predetermined portion of the tire 15. The contact timing of a predetermined portion of the tire 15 can be derived from either deformation acceleration information in the tire circumferential direction of each tire or deformation acceleration information in the tire width direction of each tire. The data processing unit 20 only needs to be able to extract at least deformation acceleration information in the tire circumferential direction of each tire and deformation acceleration information in the tire width direction of each tire from the received radio signal. However, when it is desired to derive the contact timing of a predetermined portion of the tire 15 with higher accuracy and detect the internal failure of the tire with higher accuracy, the deformation acceleration information in the tire radial direction of each tire is extracted from the received radio signal. It is preferable.

  The display 34 displays the amount of deformation in each of the tire circumferential direction and the tire width direction derived from the data processing unit 20, the determination result as to whether or not an internal failure has occurred inside the tire, and the like. Note that the display 34 indicates that an internal failure has occurred in the tire toward the driver driving the vehicle 12, particularly when the data processing unit 20 determines that an internal failure has occurred in the tire. It is also possible to issue an alarm to inform you. In the example shown in FIG. 1, the data processing unit 20 is disposed on the vehicle 12, but the data processing unit 20 is portable and is not limited to being disposed on the vehicle 12.

  FIG. 2 is a schematic configuration diagram illustrating the sensor unit 16 (sensor units 16a to 16d) and the data processing unit 20 in the apparatus 10 shown in FIG. Since the sensor units 16a to 16d have the same configuration, only the sensor unit 16a and the wheel 14a provided with the sensor unit 16a are illustrated here.

  The sensor unit 16 a includes the acceleration sensor 2 and the transmitter 17. The acceleration sensor 2 is installed on the inner peripheral surface of the hollow region of the tire 15, and a predetermined portion of the tire 15 (installation position of the acceleration sensor 1) generated when the tire 15 of each wheel receives an external force from the road surface. The acceleration information is acquired and transmitted as a wireless signal. The acceleration measurement data is transmitted from the transmitter 17 of each transmission unit to the receiver 3 of the data processing unit 20. Note that the transmitter 17 may not be provided, and for example, the acceleration sensor 2 may be separately provided with a transmission function, and may be configured to transmit from the acceleration sensor 2 to the receiver 3. Each transmitter 17 provided on each of the wheels 14a to 14d has identification information (ID) that enables identification, and the transmitter 17 measures acceleration measured by a corresponding acceleration sensor. An ID is transmitted together with the data.

  As the acceleration sensor 2, for example, a semiconductor acceleration sensor disclosed in Japanese Patent Application No. 2003-134727 filed earlier by the applicant of the present application is exemplified. Specifically, the semiconductor acceleration sensor includes a Si wafer having a diaphragm formed in the outer peripheral frame portion of the Si wafer, and a pedestal for fixing the outer peripheral frame portion, and a weight is provided at the center of one surface of the diaphragm. And a plurality of piezoresistors are formed on the diaphragm. When acceleration is applied to the semiconductor acceleration sensor, the diaphragm is deformed, and the resistance value of the piezoresistor changes due to the deformation. A bridge circuit is formed so that this change can be detected as acceleration information. This acceleration sensor is fixed to the tire inner peripheral surface so that the acceleration in the tire radial direction, the acceleration in the tire circumferential direction, and the acceleration in the tire width direction can be measured, whereby acceleration acting on the tread portion during tire rotation Can be measured. In addition to this, the acceleration sensor 2 may be an acceleration pickup using a piezoelectric element, or a strain gauge type acceleration pickup combined with a strain gauge.

  In the present embodiment, the acceleration sensor 2 is installed on the inner surface of the shoulder portion of the tire 15 (see FIG. 3). In general, the belt end of a plurality of belts stacked in the tire tread portion is located on the shoulder portion of the tire, and internal troubles such as separation during manufacturing and running compared to other portions. Likely to happen. By providing an acceleration sensor in the shoulder portion of the tire, an internal failure occurring in the tire can be detected relatively quickly. In the present invention, the number of acceleration sensors installed in each tire is not particularly limited. When it is desired to detect an internal failure of each tire with higher accuracy, a plurality of acceleration sensors 2 are preferably provided along the circumferential direction of the tire, and more preferably, a vehicle provided with the tire travels on the road surface. During the operation, it is preferable that one or more acceleration sensors are always located at the ground contact portion of the tire. It is preferable that a plurality of acceleration sensors 2 are provided in the tire width direction. However, even in the case where one acceleration sensor is installed in each tire as in the present embodiment, an internal failure occurring in each tire can be detected with more sufficient accuracy than in the past.

  The data processing unit 20 includes a receiver 3, an amplifier (AMP) 4, processing means 21, a CPU 23, and a memory 27. The data processing unit 20 is a computer in which each unit indicated by the processing means 21 functions when the CPU 23 executes a program stored in the memory 27.

  The processing means 21 includes a tire acceleration data acquisition unit 22, a signal processing unit 24, a deformation amount derivation unit 26, an evaluation value calculation unit 28, and a failure determination unit 30. The tire acceleration data acquisition unit 22 includes accelerations in the tire radial direction, accelerations in the tire circumferential direction, and tires at predetermined portions (installation positions of the acceleration sensors 2) of the tread portions of the tires 15a to 15d constituting the wheels 14a to 14d. Acquire measurement data of acceleration in the width direction. The signal processing unit 24 processes the tire radial direction acceleration data, the tire circumferential direction acceleration data, and the tire width direction acceleration data so as to process the tire radial deformation acceleration information of each tire and the tire circumferential direction data of each tire. The deformation acceleration information and the deformation acceleration information in the tire width direction of each tire are extracted, and the contact timing of a predetermined part of the tire 15 is obtained from the extracted deformation acceleration information in the tire radial direction. Then, the deformation amount deriving unit 26 uses the ground contact timing to calculate the predetermined amount in the ground contact portion of each tire 15a to 15d from the deformation acceleration data (circumferential deformation acceleration data and width direction deformation acceleration data). Deformation amounts in two directions, that is, a tire circumferential direction deformation amount and a tire width direction deformation amount of the part are derived. The evaluation value calculation unit 28 calculates an evaluation value for determining whether or not an internal failure has occurred in each tire based on the derived two-direction deformation amount. The failure determination unit 30 determines whether or not an internal failure has occurred in each tire by comparing a reference value stored in advance in the memory 27 with the calculated evaluation value. The function of each means will be described in detail later.

  The present invention obtains two deformation amounts of a tire circumferential direction deformation amount and a tire width direction deformation amount of a predetermined portion of the tread portion in each tire contact portion of each of the tires 15a to 15d. Based on this, an evaluation value for determining whether or not an internal failure of the tire has occurred is calculated. According to the present invention, an internal failure occurring in each of the tires 15a to 15d attached to the vehicle 12 can be detected easily and with high accuracy even while the vehicle 12 is traveling. FIGS. 3A and 3B are diagrams illustrating the force applied to the ground contact portions of the tires 15a to 15d when the vehicle 12 is traveling. FIG. 3A is a schematic diagram for explaining the force applied to the tread portion of the tire and the deformation of the tread portion in the ground contact portions of the tires 15a to 15d, and one tire (tire 15a) of the vehicle 12 is illustrated. It is the figure seen from the road surface side.

  As shown in FIG. 2, the tire having a substantially arc-shaped cross section is pressed against the flat road surface at the tire contact portion, so that the entire tread surface of the tire is centered on the ground as shown in FIG. It receives a force that shrinks to the part. And it deform | transforms so that the whole tread part surface of a tire may shrink | contract toward the contact center part. Since the tread portion of the tire is deformed in this manner at the ground contact portion of the tire, the acceleration sensor 2 installed on the tire passes along a locus as shown in FIG. FIG. 3B shows a time series in the tire circumferential direction of a predetermined portion of the tread portion (installation position of the acceleration sensor 2) while the acceleration sensor 2 passes through the ground contact portion shown in FIG. Is a graph showing the amount of deformation of the tire and the amount of deformation of the time series in the tire width direction, respectively, and is a graph showing the time series of deformation of a predetermined part of the tire 15a in an orthogonal coordinate system composed of the tire circumferential direction and the tire width direction. is there. As can be seen with reference to the graphs indicated by the solid lines in FIG. 3A and FIG. 3B, the predetermined portion of the tire 15a (installation position of the acceleration sensor) is the tire 15a at the beginning when the predetermined portion is grounded. The amount of deformation increases as the vehicle 12 advances (rolling of the tire 15) so as to approach the center of the ground contact portion. Then, after passing the vicinity of the center of the ground contact portion (shown as C in FIGS. 3A and 3B), the amount of deformation gradually decreases, and at the rear end of the tire ground contact portion, the deformation is almost zero ( Zero).

  The degree of deformation and the form of deformation (that is, the balance between the amount of deformation in the tire circumferential direction and the amount of deformation in the tire width direction) vary depending on the tire structure. That is, the magnitude of the deformation force applied to the tire surface (the force indicated by the arrow in FIG. 3A) and the degree of deformation of the tire surface (also indicated by the arrow in FIG. 3A). The size of the major deformation) varies depending on the surface structure and internal structure of the tire. For example, when separation occurs inside the tire, the magnitude of the deformation force applied to the tire surface (the force indicated by the arrow in FIG. 3 (a)) is transmitted to the separation portion. It is difficult and the degree of deformation is expected to be small. In addition, depending on the form of separation, the deformation force on the tire surface, the deformation of the tire surface, and the like also change between the tire circumferential direction and the tire width direction. For example, a broken line in FIG. As shown in the graph, it is expected that the tire is deformed in a different deformation form from the case where an internal failure such as separation does not occur in the tire (the graph indicated by the solid line in FIG. 3B). The processing means 21 calculates an evaluation value indicating the degree of deformation and the form of deformation of the tread portion of the tire at the ground contact portion of the tire, and an internal failure has occurred in the tire based on the calculated evaluation value. It is determined whether or not.

  As described above, the processing means 21 includes the tire acceleration data acquisition unit 22, the signal processing unit 24, the deformation amount derivation unit 26, the evaluation value calculation unit 28, and the failure determination unit 30. The tire acceleration data acquisition unit 22 is a portion that acquires, as input data, acceleration measurement data amplified by the amplifier 4 for at least one rotation of the tire. The tire acceleration data acquisition unit 22 acquires time series data of acceleration in the tire radial direction, time series data of acceleration in the tire circumferential direction, and time series data of acceleration in the tire width direction. The data supplied from the amplifier 4 is analog data, and each time series data of each acceleration is sampled at a predetermined sampling frequency and converted into digital data. The data acquisition unit 22 determines which tire acceleration measurement data the acceleration measurement data transmitted from each transmitter is based on the above-described ID transmitted from the transmitter 17 of each tire 15 (tires). 15a to 15d is determined). Thereafter, the processes performed by the signal processing unit 24, the deformation amount deriving unit 26, the evaluation value calculating unit 28, and the failure determining unit 30 are performed in parallel for the measurement data of each tire.

  The signal processing unit 24 is a part that extracts time-series data of acceleration based on tire deformation from digitized acceleration data in the tire radial direction, acceleration data in the tire circumferential direction, and acceleration data in the tire width direction. . Specifically, the signal processing unit 24 performs a smoothing process on these acceleration measurement data, calculates an approximate curve for these smoothed signals to obtain a background component 1, and this background component 1 Is removed from the smoothed acceleration measurement data, and the tire radial acceleration time series data (radial deformation acceleration data) and tire circumferential acceleration time series data (circumferential deformation) Acceleration data) and time-series data of tire width direction acceleration (width direction deformation acceleration data) based on tire deformation, respectively. The signal processing unit 24 further determines from the radial deformation acceleration data that the ground contact timing of the predetermined portion of the tire 15 (the acceleration sensor 2 fixed to the inner peripheral surface of the tire cavity region arrives at the center position of the tire ground contact surface ( (Timing closest)), that is, the timing at which the rotation angle φ shown in FIG. 2 is 180 °, 540 °, 900 °,... The extracted ground contact timing, circumferential direction deformation acceleration data, and width direction deformation acceleration data of a predetermined portion of the tire 15 are sent to the deformation amount deriving unit 26. Specific processing in the signal processing unit 24 will be described later.

  The deformation amount deriving unit 26 performs time integration of the second floor with respect to the extracted circumferential deformation acceleration data and width direction deformation acceleration data, respectively, so that time series data of the tire circumferential deformation amount (circumferential deformation amount). Data) and time-series data of tire width direction deformation amount (width direction deformation amount data). Specifically, the second-order integration with respect to time is performed for each of the circumferential direction deformation acceleration data and the width direction deformation acceleration data, and then the signal processing unit is obtained for each data obtained by the second-order integration. Using the contact timing of a predetermined part of the tire 15 extracted in 24, an approximate curve is calculated to obtain each of the background components 2, and each of the background components 2 is removed from each displacement data obtained by second-order integration. Thus, time series data of the tire circumferential direction deformation amount (circumferential deformation amount data) and time series data of the tire width direction deformation amount (width direction deformation amount data) are respectively calculated. Specific processing in the deformation amount deriving unit 26 will be described in detail later. The calculated circumferential direction deformation amount data and width direction deformation amount data are each output to the evaluation value calculation unit 28.

  The evaluation value calculation unit 28 calculates an evaluation value for determining whether or not an internal failure has occurred in the tire based on the circumferential direction deformation amount data and the width direction deformation amount data. As described above, when an internal failure such as separation occurs inside the tire, the degree of deformation and the deformation form of the tire surface change compared to the case where such an internal failure does not occur inside the tire. To do. As shown in FIG. 3B, the degree of deformation and the form of deformation of the tire surface can be expressed using circumferential direction deformation amount data and width direction deformation amount data. The evaluation value calculation unit 28 uses the circumferential direction deformation amount data and the width direction deformation amount data to calculate an evaluation value that characterizes the degree of deformation and the form of deformation of the tire surface.

FIG. 4 is a diagram illustrating an example of evaluation values in the present invention. The evaluation value calculation unit 28 first extracts the maximum value _Xmax of the circumferential deformation amount of the predetermined tire portion from the circumferential deformation amount data. Similarly, the maximum value Y _max of the width direction deformation amount of the predetermined tire portion is also extracted from the width direction deformation amount data. As described above, the tire circumferential direction deformation amount and the tire width direction deformation amount of the predetermined portion are normally maximized at the timing when the predetermined portion is closest to the center of the ground contact portion. In the present embodiment, the evaluation value calculation unit 28 uses such a maximum value X _max of the circumferential deformation amount and a maximum value Y _max of the width direction deformation amount, for example, θ = tan ⁻¹ (X _max / Y _The evaluation value θ represented by _max ) is obtained. Such an evaluation value θ can be said to be a value that characterizes the deformation form of the tire surface at the contact portion of the tire.

In the evaluation value calculation unit 28, for example, X _max × Y _max may be used as the evaluation value, and (X _max ² + Y _max ² ) ^1/2 may be used as the evaluation value. Moreover, the size of the area of the region indicated by hatching in FIG. 4 may be used as the evaluation value. Further, for example, only X _max may be used as the evaluation value, or only Y _max may be used as the evaluation value. It can be said that the evaluation value obtained in this way is a value characterizing the degree of deformation of the tire surface at the contact portion of the tire. In the present invention, it is more preferable to use an evaluation value θ represented by θ = tan ⁻¹ (X _max / Y _max ) as the evaluation value. This is because the degree of deformation of the tire ground contact portion (the amount of deformation) changes according to the running of the road surface state and the state of the vehicle (load, etc.), so the evaluation value representing the degree of deformation of the tire surface is: This is because such a fluctuation component based on the driving condition is contained in a relatively large amount as noise. By using the θ that characterizes the deformation of the tire surface as an evaluation value, it is possible to determine the presence or absence of an internal failure of the tire with higher accuracy without being affected by such fluctuation components. become.

Further, for example, a tire maximum value X _max and the maximum value Y _max of the tire width direction deformation amount of circumferential deformation of each normalized deformation amount maximum value was normalized using a predetermined value X _{max ^*,} and standardized The evaluation value may be obtained using the maximum deformation amount Y _max ^* . For example, the maximum value X _max of the tire circumferential direction deformation amount when a normal tire having the same standard (same size and air pressure) as the target of determining the internal failure and having no internal failure is mounted on the same vehicle. (normal _{X max)} and, and when the maximum value _{Y max} of the tire width direction deformation amount and the (normal _{Y max)} is known in advance, may be standardized by using these values. Incidentally, for each of a plurality of driving conditions, when the normal-time X _max and normal when Y _max is previously known, depending on the running condition of the vehicle, the normal time X _max and normal when Y _max corresponding to each travel condition It may be standardized using. Then, for example, X _max ^* × Y _max ^* may be calculated as an evaluation value using the normalized deformation maximum value X _max ^* and the normalized deformation maximum value Y _max ^* , or (X _max ^{* 2} + Y _max ^{* 2} ) ^1/2 may be calculated as the evaluation value. Further, the size of the area corresponding to the region indicated by hatching in FIG. 4 may be used as the evaluation value.

Further, for example, by using the maximum value X _max of the tire circumferential direction deformation amount and the maximum value Y _max of the tire width direction deformation amount, X _max × Y _max , (X _max ² + Y _max ² ) ^1/2 , X _max / Y _{max, Y} max _{/ X max,} obtains a calculated value for equal, the calculated value was determined by mounting a normal tire internal mechanical failure has not occurred in the same vehicle, the normal time of _{X max} and normal operation Y A value normalized by the same calculated value using _max may be used as the evaluation value. For example, X _max × Y _max is obtained using the maximum value X _max of the tire circumferential direction deformation amount and the maximum value Y _max of the tire width direction deformation amount, and this X _max × Y _max is calculated as normal X _max × normal time A value normalized using the value of Y _max may be used as the evaluation value. In this way, by standardizing using the amount of deformation when using a normal tire with no internal failure, the influence of fluctuation components based on driving conditions is reduced, and whether or not an internal failure has occurred in the tire. Thus, the determination can be made with high accuracy without being affected by such fluctuation components. The evaluation value calculated by the evaluation value calculation unit 28 (evaluation value θ in this embodiment) is sent to the failure determination unit 30. These normal time X _max and normal character Y _max may be stored in advance in the memory (storage means) of the internal failure detection device.

  The failure determination unit 30 determines whether or not an internal failure has occurred in the tire 15 by comparing the calculated evaluation value θ with a predetermined reference value. This reference value is stored in advance in the memory 27 by an input unit (not shown) and is read out by the failure determination unit 30. As such a reference value, for example, when the tire 15 is attached to the vehicle, a numerical value suitable for the tire 15 may be stored in the memory 27 by the attaching operator. Moreover, the reference value according to the specification of a vehicle or a tire may be set at the time of manufacture or shipment of the device 10 or the vehicle 12, or when the device 10 is attached to the vehicle 12. Note that, for example, when a tire that is known to have no internal failure is attached to the vehicle, only the failure that occurs while the vehicle is running becomes a problem. In such a case, every time the vehicle starts to travel, the evaluation value acquired first from the start of traveling may be stored as the reference value.

  As the reference value, for example, an evaluation value when a normal tire having the same standard (same size and air pressure) as the target of determining an internal failure and having no internal failure is mounted on the same vehicle, or such A predetermined value derived based on the evaluation value may be used. For example, the upper limit value and the lower limit value of the evaluation value θ in the case where a normal tire in which no internal failure has occurred is mounted as the reference value may be stored in advance, and the upper limit value or the evaluation value θ of the evaluation value θ may be stored. Either one of the lower limit values may be stored. The failure determination unit 30 has an internal failure in the tire 15 when the evaluation value calculated by the evaluation value calculation unit 28 is out of the range of evaluation values for normal tires stored in advance as a reference value. Can be determined.

  Alternatively, as the reference value, for example, an evaluation value when an internal failure tire having an internal failure having the same standard (same size and air pressure) as a tire for which an internal failure is determined is mounted on the same vehicle, or A predetermined value derived based on such an evaluation value may be used. When the evaluation value calculated by the evaluation value calculation unit 28 falls within the evaluation value range stored in advance as a reference value, the failure determination unit 30 has an internal failure in the tire 15. It is determined that In addition, for example, the evaluation value when an internal failure tire is mounted is standardized with the evaluation value when a normal tire without internal failure is mounted on the same vehicle, or such a standardized evaluation. A predetermined value derived based on the value may be used as the reference value.

  In the present embodiment, for example, the upper limit value and the lower limit value of the evaluation value θ in the case where the internally failed tire is mounted may be stored in advance as the reference value, and the upper limit value or the lower limit value of the evaluation value θ may be stored in advance. Either one of the values may be stored.

  The failure determination unit 30 sends a determination result to the display 34 every time a determination is made. The display 34 displays such a determination result. The display 34 can sequentially display various data and calculation results handled in the processing device 21 such as a waveform of the acquired acceleration data and various calculated parameters. In particular, when the failure determination unit 30 determines that an internal failure has occurred in the tire 15, the display 34 displays a warning display for informing the driver of the vehicle 12 that an internal failure has occurred. To do. In addition to the display 34, the device 10 more preferably includes alarm generation means for notifying the driver of the vehicle 12 that an internal failure has occurred by sound.

  FIG. 5 is a flowchart of the tire internal failure detection method of the present invention that is implemented in such an apparatus 10. 6 to 7 show an example of a result obtained by each process in the apparatus 10. The results shown in FIGS. 6 to 7 are all processing results for the tire radial direction acceleration data measured by the acceleration sensor 2. Hereinafter, the tire internal failure detection method of the present invention implemented in the apparatus 10 will be described in detail using the tire radial acceleration data as an example.

  First, the measurement data of the acceleration of each tire amplified by the amplifier 4 is supplied to the data acquisition unit 22, sampled at a predetermined sampling frequency, and digitized measurement as shown in FIG. 6 (a). Data is acquired (step S102). At this time, as described above, the data acquisition unit 22 determines which tire acceleration measurement data is the acceleration measurement data transmitted from each wheel based on the above-described ID transmitted from each transmitter 15. (Which wheel is tire 15a to tire 15d) is determined. The subsequent processing is performed for each acceleration measurement data of each tire.

  Next, the acquired measurement data is supplied to the signal processing unit 24, and first, smoothing processing using a filter is performed (step S104). As shown in FIG. 6A, since the measurement data supplied to the signal processing unit 24 includes a lot of noise components, the smoothing processing results in smooth data as shown in FIG. 6B. For example, a digital filter having a predetermined frequency as a cutoff frequency is used as the filter. The cut-off frequency varies depending on the rolling speed and noise components. For example, when the rolling speed is 60 (km / hour), the cut-off frequency is set to 0.5 to 2 (kHz). In addition, a smoothing process may be performed using a moving average process, a trend model, or the like instead of the digital filter.

  Next, the signal processing unit 24 removes the low-frequency background component 1 from the smoothed acceleration measurement data (step S106). The background component 1 of the tire acceleration includes the effects of the acceleration component of gravity and the acceleration component of gravity during rolling of the tire. In FIG. 6B, the waveform of the background component 1 is shown. The extraction of the low frequency component is performed by further performing a smoothing process on the waveform data after the smoothing process obtained in step S104. For example, a digital filter having a predetermined frequency as a cutoff frequency is used. For example, when the rolling speed is 60 (km / h), the cutoff frequency is set to 0.5 to 2 (kHz). In addition, a smoothing process may be performed using a moving average process, a trend model, or the like instead of the digital filter. Further, in the waveform data after the smoothing process, for example, a plurality of nodes are provided at predetermined time intervals, and a first approximate curve is obtained by a least square method using a predetermined function group, for example, a cubic spline function. You may obtain | require by calculating. The node means a constraint condition on the horizontal axis that defines the local curvature (flexibility) of the spline function. The signal processing unit 24 subtracts the background component 1 extracted in this way from the acceleration measurement data smoothed in step S104, so that the acceleration component based on the rotation of the tire and the gravitational acceleration component are obtained from the measurement data. Removed. FIG. 6C shows time-series data of acceleration after removal. Thereby, the component of acceleration based on the ground deformation of the tread portion of the tire (time series data of acceleration based on the deformation of the tire) can be extracted.

Further, the signal processing unit 24 obtains the rotation angle φ shown in FIG. 2 from 180 °, 540 °, 900 °,... From the time series data of the acceleration based on the tire deformation obtained as described above. Each timing is extracted (step S108).
In the signal processing unit 24, in the graph of the time series data of the acceleration based on the tire deformation, the timing at which the acceleration based on the tire deformation takes the minimum value, the rotation angle φ is θ = 180 °, 540 °, 900 °. Extracted as the timing of. That is, the timing of these minimum values is extracted as the timing at which the acceleration sensor 2 fixed on the inner peripheral surface of the tire cavity region arrives (closest) to the center position of the tire contact surface as shown in FIG. In the tire contact area, the position of the outer peripheral surface of the tire in the direction perpendicular to the road surface is defined by the road surface. In the contact area, the road surface deforms the tire outer peripheral surface, which is originally curved, on a flat surface, so that the tire deforms in the thickness direction. As a result, the position of the inner peripheral surface of the tire cavity region fluctuates in the tire thickness direction (direction perpendicular to the road surface) in the ground contact region. The deformation in the thickness direction of the tire is minimized at the center position of the contact surface. The timing at which the acceleration in the tire radial direction based on the deformation of the tire, which is obtained by the acceleration sensor arranged on the inner peripheral surface of the tire cavity region, becomes the minimum is the rotation angle φ described above is 180 °, 540 °, 900 °. It can be said that this is the timing. Note that the timing at which each of the above-mentioned rotations φ becomes 180 °, 540 °, and 900 ° can be derived using either one of the deformation acceleration in the tire circumferential direction and the deformation acceleration in the tire width direction. Can do. Each process from step S104 to step S108 is performed on the acceleration measurement data of each of the wheels 14a to 14d acquired in step S102.

  Next, using the processing result in the signal processing unit 24, the deformation amount deriving unit 26 derives the circumferential direction deformation amount data and the width direction deformation amount data of each of the tires 15a to 15d of the traveling vehicle 12 ( Step S110). FIGS. 7A to 7C are graphs schematically showing the processing results performed by the deformation amount deriving unit 26 in step S110. In the deformation amount deriving unit 26, first, time integration data of acceleration based on the ground deformation is subjected to second-order time integration to generate displacement data. FIG. 7A shows a result of second-order integration with respect to time of time series data of acceleration from which the first background component has been removed in the data processing unit. As shown in FIG. 7A, it can be seen that the displacement increases with time. This is because the time series data of acceleration to be integrated includes a noise component, and this noise component is also integrated by integration. In general, when the amount of deformation or displacement at a point of interest in a tread portion of a tire that rolls in a steady state is observed, a periodic change is shown in units of the tire rotation cycle. Therefore, it is usually not possible for the displacement to increase with time. Therefore, the following processing is performed on the displacement data so that the displacement data obtained by performing the second-order time integration shows a periodic change in units of the tire rotation cycle.

  That is, the noise component included in the displacement data is calculated as the background component 2 in the same manner as the method for calculating the background component 1. At this time, the deformation amount during rolling of the tire in the region including the contact area with the road surface can be obtained with high accuracy by using the time-series rotation angle obtained in the derivation of the centrifugal force. More specifically, the area on the circumference of the tire is divided into a first area including a contact area with the road surface and a second area other than this, and the first area is larger than φ = 90 degrees 270. An area of less than 85 degrees, greater than 450 degrees and less than 720 degrees, greater than 810 degrees and less than 980 degrees, and φ = 0 degrees to 90 degrees and 270 degrees to 360 degrees, 360 degrees to 450 degrees as the second areas The following regions are defined: 630 ° to 720 °, 720 ° to 810 °, and 980 ° to 1070 °. The background component 2 uses the plurality of circumferential positions (φ or time corresponding to φ) in the second region as nodes, and uses a predetermined function group to set the first region and the second region. It calculates | requires by calculating a 2nd approximation curve with the least squares method with respect to the data of an area | region. The node means a constraint condition on the horizontal axis that defines the local curvature (flexibility) of the spline function. In FIG. 7B, a second approximate curve representing the background component 2 is indicated by a dotted line. In the example of FIG. 7B, the position indicated by “Δ” in FIG. 7B, that is, φ = 10, 30, 50, 70, 90, 270, 290, 310, 330, 350, 370, 390. , 410, 430, 450, 630, 650, 670, 690, 710, 730, 750, 770, 790, 810, 990, 1010, 1030, 1050, 1070 degrees.

  A second approximate curve indicated by a dotted line in FIG. 7B is calculated by performing function approximation on the displacement data shown in FIG. 7A with a cubic spline function passing through the data points of the nodes. Is done. When performing function approximation, there are no nodes in the first region, function approximation is performed using only a plurality of nodes in the second region, and the weighting factor of the second region used in the least square method performed in function approximation is used. The processing is performed with 1 being set to 1, and the weighting coefficient of the first region being set to 0.01. Thus, when calculating the background component 2, the first weighting factor is reduced and the node is not defined in the first region. The background component 2 is calculated mainly using the displacement data in the second region. It is to do. In the second region, deformation due to contact of the tread portion is small and the deformation changes smoothly on the circumference, so that the amount of deformation of the tire is small on the circumference and the change is also extremely small. On the other hand, in the first region, the tread portion of the tire is greatly displaced and rapidly changes based on the ground deformation. For this reason, the amount of deformation based on ground deformation is large and rapidly changes on the circumference. That is, the deformation amount of the tread portion in the second region is substantially constant as compared with the first deformation amount. Thus, by calculating the first approximate curve mainly using the displacement data obtained by the second order integration of the second area, the first area including not only the second area but also the ground contact area with the road surface is obtained. The amount of deformation during rolling of the tire in the region can be obtained with high accuracy. In FIG. 7B, a second approximate curve calculated mainly using the displacement data of the second region is indicated by a dotted line. In the second region, the second approximate curve substantially matches the displacement data (solid line).

  Then, the approximate curve calculated as the background component 2 is subtracted from the displacement data, and the distribution of the deformation amount based on the ground deformation of the tread portion is calculated. FIG. 7C shows the distribution of deformation based on the ground deformation of the tread portion, which is calculated by subtracting the second approximate curve (dotted line) from the displacement signal (solid line) shown in FIG. 7B. Show. FIG. 7C shows a distribution of deformation amounts for three rotations (three times of ground contact) when a predetermined measurement position on the tread portion is rotated around the circumference and displaced. It can be seen that the amount of deformation changes with each contact. The deformation amount calculated by such a method coincides with the deformation amount when the simulation is performed using the tire finite element model with high accuracy. The deformation amount deriving unit 26 performs such processing for each of the circumferential direction deformation acceleration data and the width direction deformation acceleration data, and obtains the circumferential direction deformation amount data and the width direction deformation amount data, respectively.

Next, the evaluation value calculation unit 28 calculates the evaluation value (step S112). The evaluation value calculation unit 28 extracts the maximum value X _max of the tire circumferential direction deformation amount from the circumferential direction deformation amount data, and similarly extracts the maximum value Y _max of the tire width direction deformation amount from the width direction deformation amount data. To do. Then, for example, an evaluation value θ represented by θ = tan ⁻¹ (X _max / Y _max ) is obtained.

  Then, the failure determination unit 30 compares the evaluation value θ calculated by the evaluation value calculation unit 28 with the reference value stored in advance in the memory 27 to determine whether an internal failure has occurred, Determination is made for each tire (step S114). If there is a tire determined to have an internal failure in step S114, the display 34 displays a warning notifying the driver driving the vehicle 12 that there is a tire having an internal failure. At this time, it is preferable to display a warning in a form that allows the driver to determine which of the tires 15a to 15d is the tire in which the internal failure has occurred. When the failure determination unit 30 determines that there is no tire in which an internal failure has occurred, such warning display is not performed. The series of processes shown in steps S102 to S116 is repeatedly performed until the determination of step S118 is YES, for example, when the driver gives an instruction to end the measurement or the vehicle 12 is stopped. . The tire internal failure detection method of the present invention is performed in this way.

  FIGS. 8A to 8D are diagrams for explaining the effects of the tire internal failure detection method of the present invention. Each graph shown in FIGS. 8A to 8D shows a tire A in which a tire internal failure such as separation does not occur, and a tire B having the same standard d as the tire A and separation in the shoulder portion. It is a graph about two tires. More specifically, in each graph shown in FIGS. 8A to 8D, acceleration sensors are installed on the inner surfaces of the shoulder portions of the tire A and the tire B, and the tire A and the tire B are subjected to various conditions. The circumferential deformation amount data and the width of a predetermined portion (installation portion of the acceleration sensor) on each surface of the tires A and B obtained by rolling with a known indoor drum durability tester (drum diameter 2500 mm) The direction deformation data is shown. Both the tire A and the tire B are tires having a tire size of 195 / 65R15, and the filling air pressure was 200 kPa in both cases. In the shoulder portion of the tire B, the belt member and the rubber member are separated from each other over an area of 4 mm in the tire width direction and 120 mm in the tire circumferential direction by devising at the time of manufacturing the tire B. In the tire B, an acceleration sensor is installed in the very vicinity of the separation unit, and in the tire A, the acceleration sensor is installed at a position corresponding to the acceleration sensor installation position in the tire B.

  FIG. 8A shows the variation of the evaluation value θ of each of the tire A and the tire B according to the change in the travel time of the vehicle. Deformation amount data (circumferential deformation amount data and width direction deformation amount data) at the time of elapse, and deformation amount data (circumferential direction deformation amount data and width direction deformation amount) after 20 minutes from the start of the durability test, and Are shown for tire A and tire B, respectively. In the example shown in FIG. 8A, both the tire A and the tire B have a contact load of 4 kN and a rolling speed of 60 km / h under any condition (any time point). It should be noted that the tire temperature is not warmed after 2 minutes have elapsed from the start of travel, and the tire temperature is greater when 20 minutes have elapsed from the start of travel between the time when 2 minutes have elapsed from the start of travel and the time when 20 minutes have elapsed since the start of travel. It was rising.

As shown in FIG. 8A, the evaluation value θ _A of the tire A (in FIG. 8A, only shown after traveling 2 min) and the evaluation value θ _B of the tire _B (in FIG. 8A). However, even though the elapsed time from the start of running changed, no significant change was observed in each tire. That is, the difference in the deformation form between the tire A and the tire B caused by the change in the tire temperature was small as compared with the difference in the deformation form between the tire A and the tire B caused by the presence or absence of the separation of the tire. . For example, when the lower limit value θ ₀ as shown in FIG. 8A is set as the reference value, the evaluation value of the normal tire A is always larger than θ ₀ even if the running time (that is, the tire temperature) changes. , the evaluation value of the tire B that separation has occurred is smaller than the always θ _0.

8 (b) and 8 (c) show the variation of the evaluation value θ according to the change in the rolling speed of the evaluation value θ of each of the tire A and the tire B. The rolling speed is 40 km / h, Deformation amount data (circumferential deformation amount data and width direction deformation amount data) at each rolling speed when changing to 60 km / h and 80 km / h are shown for tire A and tire B, respectively. In the example shown in FIG. 8B, the ground load is set to 3 kN for both the tire A and the tire B under any condition (any rolling speed condition). In the example shown in FIG. 8C, both the tire A and the tire B have a ground load of 4 kN. As shown in FIG. 8B and FIG. 8C, the evaluation value θ _A for the tire _A (shown only in the case of a rolling speed of 40 km / h in FIG. 8) and the evaluation for the tire B Although there is a significant difference from the value θ _B (shown only in the case of a rolling speed of 40 km / h in FIG. 8), the only noticeable difference in the tire deformation amount for each tire is that the rolling speed is changed. I couldn't see it. That is, the difference in the deformation mode between the tire A and the tire B corresponding to the change in the tire rolling speed is small compared with the difference in the deformation mode between the tire A and the tire B caused by the presence or absence of the tire separation. Met. For example, when the lower limit value θ ₀ of the evaluation value θ is set as the reference value, even if the tire rolling speed changes, all the evaluation values of the normal tire A are larger than θ ₀ and separation occurs. evaluation value of the tire B is smaller than ₀ none theta.

FIG. 8 (d) shows the variation of the evaluation value according to the change in the grounding load of the evaluation value θ of each of the tire A and the tire B. When the grounding load is changed to 3 kN, 4 kN, and 5 kN, FIG. The deformation amount data (circumferential deformation amount data and width direction deformation amount data) at each contact load is shown for each of tire A and tire B. In the example shown in FIG. 8 (d), both the tire A and the tire B have a rolling speed of 60 km / h under any condition (any contact load condition). As shown in FIG. 8 (d), _(8, when the ground contact load 3kN shows only for) evaluation value theta _A Tire A and, in the evaluation value theta _{B (FIG.} 8 of the tire B, ground Although only a large difference is shown, the tire deformation amount was not noticeably changed in each tire only by changing the ground load. That is, the difference in deformation form between the tire A and the tire B in accordance with the change in the contact load of the tire is small as compared with the difference in deformation form between the tire A and the tire B caused by the presence or absence of the tire separation. Met. For example, when the lower limit value θ ₀ of the evaluation value θ is set as the reference value, even if the tire ground contact load changes, all the evaluation values of the normal tire A are larger than θ ₀ and separation occurs. evaluation value of B is smaller than _zero both θ.

Thus, as can be seen from the graphs shown in FIGS. 8 (a) to 8 (d), which are the results of experiments performed using the indoor drum durability tester, traveling such as tire temperature, rolling speed, and ground load is performed. Even if the conditions change, for example, the difference in the deformation form of the tire characterized by the evaluation value θ is relatively small. On the other hand, the difference in the deformation form of the tire is relatively large when an internal failure such as separation occurs in the tire and when no internal failure occurs in the tire. In the present invention, the presence or absence of occurrence of an internal failure of the tire is determined based on such a deformation form of the tire, so that it is affected by changes in running conditions such as tire temperature, rolling speed, and ground contact load. Therefore, it is possible to detect the occurrence of an internal failure of the tire with high accuracy. When the tire internal failure detection method and the tire internal failure detection device of the present invention are used, θ ₀ is set as a reference value, and it is determined that an internal failure has occurred when the evaluation value θ is below θ _0. 8A to 8D, the tire B is a tire in which an internal failure has occurred, and the tire A is a normal tire in which no internal failure has occurred. Accurate detection results of internal faults can be obtained.

Tables 1 and 2 below show examples of evaluation values obtained under the respective traveling conditions, which are obtained from the respective deformation amount data shown in the respective graphs of FIG. 8. . In Table 1 and Table 2 below, for tire A and tire B, the circumferential direction deformation maximum value _Xmax and the width direction deformation maximum value _Ymax are substituted into the equations shown on the left side of Tables 1 and 2. Each calculated value is obtained, and an evaluation value is derived using each calculated value. In Table 1 below, the calculated value of the tire A for each driving condition is set to 100 (for this reason, the evaluation values of the tire A are all 100 in Table 1). A relative value obtained by standardizing the calculated value of the tire B for each traveling condition with the calculated value of the tire A under the corresponding traveling condition is used. Further, in the following Table 2, the calculated value of the tire A under one predetermined traveling condition (rolling speed 60 km / h, ground load 4 kN, air pressure 200 kPa) is 100. The relative values obtained by normalizing the calculated values of the tire A and the tire B with the calculated values of the tire A under the predetermined condition are used as the evaluation values of the tire A and the tire B, respectively. In Tables 1 and 2, the evaluation value represented by ∫ (Xi * Yi) is a value (circumferential deformation amount and width direction deformation) corresponding to the size of the area indicated by hatching in FIG. It is the value obtained by integrating the quantity with respect to time).

In the right end column of Table 1, the range indicated by each evaluation value for the tire B is shown. Moreover, the range which each evaluation value shows about the tire A and the tire B is shown by the right end column of Table 2, respectively. When the range indicated by each evaluation value shown in Table 2 is compared between the tire A and the tire B, the evaluation value can be used regardless of which evaluation value is used except when only the circumferential deformation amount is used as the evaluation value. The range of values that can be taken differs between tire A and tire B. As can be seen from Tables 1 and 2, when the calculated value of the tire subject to internal failure determination is normalized using the calculated value of a normal tire as the evaluation value, the calculated value is Y _max If the evaluation value of the tire subject to internal failure determination is 75 or less, more preferably 50 or less, it may be determined that an internal failure has occurred in the tire. When the calculated value is X _max * Y _max, it is determined that an internal failure has occurred in the tire when the evaluation value of the tire subject to internal failure determination is 60 or less, more preferably the evaluation value is 45 or less. do it. Further, when the calculated value is (X _max + Y _max ) ^1/2 , when the evaluation value of the tire subject to internal failure determination is 75 or less, more preferably when the evaluation value is 55 or less, the tire has internal failure. What is necessary is just to determine with having generate | occur | produced. Further, when the calculated value is ∫ (Xi * Yi), when the evaluation value of the tire subject to internal failure determination is 60 or less, more preferably when the evaluation value is 45 or less, an internal failure has occurred in this tire. What is necessary is just to judge. When the calculated value is X _max / Y _max , when the evaluation value of the tire subject to internal failure determination is 130 or more, more preferably when the evaluation value is 150 or more, it is determined that an internal failure has occurred in the tire. do it. Further, when the calculated value is Y _max / X _max , when the evaluation value of the tire subject to internal failure determination is 80 or less, more preferably when the evaluation value is 60 or less, it is determined that an internal failure has occurred in the tire. do it.

  As described above, the tire internal failure detection method and the tire internal failure detection method of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. Of course.

It is a schematic block diagram explaining an example of the tire internal failure detection apparatus of this invention. It is a figure explaining the sensor unit and the data processing unit in the tire internal failure detection apparatus shown in FIG. (A) And (b) is a figure explaining the force concerning the grounding part of a tire at the time of driving | running | working of a vehicle, (a) is the figure which looked at the tire of the vehicle shown in FIG. 1 from the road surface side, (B) is a graph showing the time-series deformation amount in the tire circumferential direction and the time-series deformation amount in the tire width direction of the tire, respectively. It is a figure explaining the example of the evaluation value in this invention. It is a flowchart figure of an example of the tire internal failure detection method of this invention. (A)-(c) has shown an example of the result obtained by the process in the signal processing part of the data processing unit shown in FIG. (A)-(c) has shown an example of the result obtained by the process in the deformation | transformation amount derivation | leading-out part of the data processing unit shown in FIG. (A)-(d) is a figure for demonstrating the effect of the internal failure detection method of the tire of this invention, and the circumferential direction deformation | transformation data and the width direction of the predetermined site | part of each surface of the tire A and the tire B Deformation amount data is shown.

Explanation of symbols

2 Acceleration sensor 3 Receiver 4 AMP
DESCRIPTION OF SYMBOLS 10 Tire internal failure detection apparatus 12 Vehicle 14a-14d Wheel 15a-15d Tire 16a-16d Sensor unit 17 Transmitter 20 Data processing unit 21 Processing means 22 Tire acceleration data acquisition part 23 CPU
24 signal processing unit 26 deformation amount deriving unit 27 memory 28 evaluation value calculating unit 30 failure determining unit 34 display

Claims (10)

In a vehicle including wheels equipped with tires, an apparatus for detecting an internal failure occurring inside the tire while the vehicle is running,
Tire information acquisition means for acquiring tire information relating to the tire during rolling;
Based on the tire information, deformation amount deriving means for deriving the deformation amount of the ground contact portion of the tire while the vehicle is traveling,
Evaluation value calculating means for calculating an evaluation value for determining whether or not the internal failure has occurred, based on the derived deformation amount;
A determination means for determining whether an internal failure has occurred in the tire by comparing the calculated evaluation value with a predetermined reference value;
A tire internal failure detection device comprising: The tire information acquisition means acquires, as the tire information, time-series acceleration data of a predetermined portion of the tire that is generated when the rolling tire receives an external force from the road surface,
The deformation amount deriving unit obtains the deformation amount of the ground contact portion of the tire using time-series acceleration data of the tire acquired by the tire information acquiring unit. Tire internal failure detection device.   The deformation amount derivation means extracts time-series acceleration data based on tire deformation from the time-series acceleration data, and performs second-order time integration on the time-series acceleration data based on the tire deformation. The tire internal failure detection device according to claim 2, wherein the deformation amount of the tire is calculated by performing displacement data calculation. The deformation amount deriving means obtains at least two deformation amounts in a circumferential direction of the tire and a deformation amount in the width direction of the tire, at least in the ground contact portion of the tire,
The evaluation value calculating means calculates the evaluation value based on a deformation amount in two directions, that is, a circumferential deformation amount in the tire contact portion and a width deformation amount in the tire contact portion. The tire internal failure detection device according to any one of claims 1 to 3. When the maximum value of the circumferential deformation amount at the ground contact portion of the tire is X _max and the maximum value of the width direction deformation amount is Y _max ,
The tire internal failure detection device according to claim 4, wherein the evaluation value is a value represented by using either X _max / Y _max or Y _max / X _max . The tire according to claim 5, wherein the evaluation value is a value expressed by using either tan ⁻¹ (X _max / Y _max ) or tan ⁻¹ (Y _max / X _max ). Internal failure detection device. When the maximum value of the circumferential deformation amount at the ground contact portion of the tire is X _max and the maximum value of the width direction deformation amount is Y _max ,
The tire internal failure detection device according to claim 4, wherein the evaluation value is X _max × Y _max . The deformation amount derivation step obtains a circumferential deformation amount of the tire at a contact portion of the tire,
The tire internal failure detection device according to any one of claims 1 to 3, wherein the evaluation value calculation step calculates the evaluation value based on a maximum value of the circumferential deformation amount. In the deformation amount derivation step, a tire width-direction deformation amount in a contact portion of the tire is obtained,
The tire internal failure detection device according to claim 1, wherein the evaluation value calculation step calculates the evaluation value based on a maximum value of the width direction deformation amount. In a vehicle including wheels equipped with tires, a method of detecting an internal failure occurring inside the tire while the vehicle is running,
A tire information acquisition step of acquiring tire information relating to the tire in rolling;
Based on the tire information, a deformation amount derivation step for deriving a deformation amount of the ground contact portion of the tire while the vehicle is traveling,
An evaluation value calculating step for calculating an evaluation value for determining the presence or absence of occurrence of the internal failure based on the derived deformation amount;
A determination step of determining whether or not an internal failure has occurred inside the tire by comparing the calculated evaluation value and a predetermined reference value;
A tire internal failure detection method comprising:

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